The subject matter disclosed herein relates to a spark plug and, in particular, to an insulator of a spark plug.
Spark plugs used as igniters in an internal combustion engine are subjected to a condition known as “fouling.” Over time, carbon and other products of combustion can accumulate on the spark plug, including the surface of an insulator tip of the spark plug, which is typically positioned at or near a boundary of unmixed fuel, or at or near the center electrode tip. The products of combustion of a gasoline engine include particles of fuel additives such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT) and Ferrocene, which are often added to gasoline as an octane enhancement. Normally, accumulated soot that is located near the spark point of the spark plug would be burned off from the heat of the generated spark. However, because the exposed surface of the insulator tip may not be located in or about a spark gap between the electrode tip and ground electrode, accumulated combustion soot may not be burned off. If significant amounts of these combustion products are accumulated, the spark may not properly form between the center and ground electrodes. The accumulated combustion soot creates an electrical short circuit such that the charge from the center electrode travels across the surface of the insulator and back to the outer metal shell instead of across the spark gap to the ground electrode. This process is called “fouling.”
Accordingly, while existing spark plugs are suitable for their intended purposes, the need for improvement remains, particularly in providing a spark plug that is more resistant to fouling caused by the accumulation of combustion products on the insulator tip.